Drawing on the framework of Modality from systemic functional linguistics, the present study aimed to explore adolescent ESL learners' interpersonal meaning-making. Data were collected from 10 writing tasks completed by a group of 50 adolescent ESL learners in China. Functional text analysis was utilized to analyze the data, including Modality types, orientation, value, and polarity. The finding revealed that overuse of certain types of modal verbs is common in Chinese ESL learners' writing, for instance, the case of "can". Most of the modality deployed was simple and congruent. In conclusion, systematic introduction of Modality and the provision of more contexts for learners to practice them are highly recommended in such a context.